Impact-tool



(No Model.) Y 4 Sheets-Sheet 1. T. H. PHILLIPS.

IMPACT TOOL.

Patented Oct. 19,1897.

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T. H. PHILLIPS.

IMPAGTTOOL.

No. 592,166. Patented Oct. 19,1897

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;UNITED STATES PATENT O FICE.

THOMAS H. PHILLIPS, OF ST. DAVIDS, PENNSYLVANIA.

IM PACT-TOOL.

SPECIFICATION forming part of Letters Patent No. 592,166, dated October19, 1897.

Application filed April 30,1897.

To on whom it may concerns I Be it known that I, THOMAS H. PHILLIPS,

a citizen of the United States, residing in St.

My invention consists of certain improve-' ments in impact-tools, suchas rockdrills using steam,'compressed air, or other expansiblemotivefiuid, which, for convenience, in this specification I will referto simply as steam.

The objects of my invention are, first, to insure the free exhaust ofthe steam from the rear end of the cylinder, so as to avoid backpressure on the piston on the return stroke; second, to delay theadmission of steam to the front end of the cylinder until the blow hasbeen struck, thereby securing an uncushioned blow; third, to accomplishthese results by the employment of a single valve and to so control themovement of said valve that it will be cushioned and prevented fromviolently striking the buffer at either end of the valve-chest, and,fourth, to simplify and cheapen the construction of the tool. Theseobjects I attain in the manner hereinafter set forth, reference beinghad to the accompany-w ing drawings, in which-- Figure 1 is alongitudinal section of an impact-tool constructed in accordance with myinvention. Fig. 2 is a view partly in elevation 'and partly in sectionalplan on the'line w x, Fig.1. i Fig. 3 is a transverse section partly onthe line 1 y and partly on the line w to, Fig. 1, omitting the valve;and Figs. 4,

5, 6, 7, 8, and 9 are diagrams illustrating the operation of the tool.

The cylinder 1 contains the piston 2, which is constructed, as usual,with opposite heads having between them a central recessed portion,forming a live-steam chamber which is in constant communication with themain inlet through one or other, or both, of the steam-inlet ports 3,the latter communicating in any available manner with the steaminletchannel 4, to which steam may be ad.- mitted from either side, as mostconvenient, the opening at the other side being properly closed.

Mounted upon the cylinder at one side of the same is a valve-chest 5,having central ports Serial No. 634,601. on model.)

or passages 6, communicating with exhaustchannelsat opposite sides ofthe chest, so that the exhaust may be taken from either side, the otherside being closed. The valve-chest has suitable end caps 7 and internalbufferplates 8, between which and the end caps are placed springs ormasses-of elastic or semielastic material 9, so that elastic buifers areprovided at each end of the valve-chest for receiving the impact of thevalve 10. The latter is an ordinary spool-valve having opposite enddisks connected by a contracted stem so as to form a central channel orchamher, and it operates in conjunction with certain ports 11, 12, 13,and 14, formed in the valve-chest. The port 11 communicates directly,and the port 12 communicates, through the valve-chest and a port 11,with a passage 11, which communicates with the interior of the cylinderthrough a port 15, located in said cylinder some distance in advance ofthe longitudinal center of the same, and the port 12 communicates with apassage 16, which has a port 17 atthe front end of the cylinder andanother. port 18 some distanceinward from said end port. A port 19 oflimited area provides a communication between the interior of thecylinder and the passage 11 at a point some distance rearwardly from theport 15. The port 13 communicates with a passage 20, which terminates ina port 21, located in the cylinder some distance in advance of the rearend of the same, and the 'port 14 communicates with a passage 22, whichleads directly from said port to the cylinder. A port 23 near the rearend of the cylinder communicates through a passage 24 with a port 25,formed in the cylinder at a point some distance in advance of the port23, the forward edge of the port 25 and the forward edge ofthe passage22 being preferably in the same transverse plane.

In the passage 16, between the ports17 and 18 of the same, is located achoke-plate 26 of the character set forth in my Patent No. 561,030,dated May 26, 1896, the purpose of this choke-plate being to provide forrestricting the fiow of steam into the front end of the cylinder throughthe port 17 as desired. A passage 27 leads from the port 17 to the platewhich closes the front end of the cylinder, so that steam can enter thecylinder at its extreme forward end, and a passage 28 leads from theport 23 to the plate which closes the rear end of the cylinder, saidpassage 28 being of limited area in cross-section to assist incushioning the piston.

The operation of the tool will be understood on reference to Fig. 1, andto the diagrammatic views Figs. 4 to 9, inclusive. As shown in Fig. 1,the piston is at the extreme rear end of its stroke and steam isentering the rear end of the cylinder through the rear port 3, thecentral chamber of the piston, the port 25, passage 24, port 23, andpassage 28, the valve 10 occupying a position at the forward end of thevalve chest, so that the forward end of the cylinder is open to theexhaust through the ports 17 and 18, passage 16, and ports 12 and 6.Steam under pressure enters the rear end of the valve-chest through thepassage 22 and port It, so as to maintain the valve in its forwardposition in the chest. As the piston moves forward in'the cylinder thefirst effect of the movement is to cut off the flow of steam into therear end of the cylinder by the closing of the port 25 by the rear headof the piston, as shown in Fig. 4, this same m ovement also closing thepassage 22. Steam new acts expansively in the rear end of the cylinderto continue the forward movement of the piston, and the port 21 isuncoveredso as to open communication between the rear end of thevalve-chest and the rear end of the cylinder and equalize the pressuretherein. As the piston continues to move forward its front end uncoversthe small port 10, as shown in Fig. 5, and thus permits steam in limitedvolume to enter the passage 11, and thence, through the port 11, to gainaccess to the forward end of the valve-chest. By this means pressure isaccumulated in the forward end of the valve-chest, but as this pressureis exerted against the pressure, somewhat reduced by expansion, at therear end of the chest, it does not effect a quick rearward movement ofthe valve 10, but simply serves to overcome the inertia of said valve,or move it slowly rearward, so that by the time the front head of thepiston, in its forward movement, uncovers the port 15, as shown in Fig.6, and thereby admits the full volume of steam to the front end of thevalve-chest, the valve is in condition to move promptly under thispressure. The first effectof the movement of the valve is to uncover theport 13, as shown in Fig. 6, and thereby open the rear end of thecylinder to the exhaust through port 21, passage 20, and ports 13 and 6.The ports 12 and 13 are so disposed in respect to the valve that theport 13 is opened to the exhaust before the port 12 is opened to thesteam, so that while there-is a free exhaust of the steam from the rearend of the cylinder in order to prevent back pressure upon the piston onthe return stroke, the admission of steam to the forward end of theeylinder is delayed because of this action of the valve, and alsobecause the final portion of the rearward movement of the valve isretarded by the cushioning effect of the steam trapped in the rear endof the valve-chest, which steam must be forced from said rear end of thevalve-chest either forwardly around the rear disk of the valve, orrearwardly around the rear head of the piston, or partly through bothavenues of escape, the disks of the valve and heads of the piston havinga reasonably neat fit in the valve-chest and cyl inder, respectively.Hence by the time the port 12 is opened, as shown in Fig. 7, and steamin any considerable volume can enter the front end of the cylinder andact upon the forward head of the piston, the latter, owing to thegreater velocity with which it moves as compared with that of the valve,has reached the forward limit of its stroke, as shown in F1 g. 7 ,andthe blow has been delivered. Hence there is no cushioning of the blow,such as results from the premature admission of steam to the forward endof the cylinder. The piston is now forced rearwardly in the cylinder,the full steam-pressure being exerted until the piston reaches theposition shown in Fig. 8, where the front head of the piston closes theport 15 and thus cuts off the flow of steam into the forward end of thecylinder, with the exception of the limited flow through the port 19,this flow being also cut off soon after. The expansion of the steam inthe forward end of the cylinder begins, however, as soon as the port 15is closed, and continues until the piston reaches the position shown inFig. 9, so as to again open the port 25 and passage 22 and permit livesteam to enter the rear end of the cylinder and the rear end of thevalvechest. The admission of steam to the rear end of the cylinder, itwill be observed, is not controlled by the valve. Hence the movement ofthe latter cannot delay the admission of steam in full volume to saidrear end of the cylinder, so as to properly cushion the piston on theback stroke and prevent injury to the rear head of the cylinder bycontact of the piston therewith. As the valve moves forward in thevalve-chest it opens the front end of the cylinder to the exhaustthrough the ports 17 and 18, passage 16, and port 12, the final movementof the valve being cushioned in the same manner as its backward movementby the necessity of forcing the trapped steam from the front end ofthevalvc-chest, either backwardly around the forward disk of the valveor forwardly around the front head of the piston, or both. Free exhaustof steam from the front end of the cylinder is provided by the port 18irrespective of the obstructive action of the choke-plate 26. The ports19 and 22 are preferably so disposed in reference to each other and tothe heads of the piston that one will be opened just as the other isclosed, so that there will always be live-steam pressure in one or otherend of the valve-chest. As the valve is moved by the difference inpressure in the front and rear ends of the valve-chest, it must ofnecessity move less rapidly than if one end of the valve-chest was opento the exhaust and there was no back pressure upon the valve, and as thevolume of steam to be exhausted from the rear end of the cylinder isconsiderably larger than that to be exhausted from the front end it isimportant that the valve be started promptly on itsrearward movement.Hence steam is admitted in limited volume tothe front end of thevalve-chest in order to overcome the inertia of the valve or start thesame before the steam is admitted in full volume to said front end ofthe valve-chest by the uncovering of the port 15. Instead of using thesmall port 19 in the rear of the main port 15, a passage of contractedareasuch, for instance, as the passage 27 or 2S- may lead rearwardlyfrom the port to the desired extent, the result-namely, the admission ofsteam to the valve-chest in limited volume before the opening of theport.15 being the same in either case.

Having thus described my invention, I claim and desire to secure byLetters Patent 1. An impact-tool in which are combined a cylinder, avalve-chest, a valve in said chest, a reciprocating piston whereby thefiow of steam to the valve-chest is governed, passages for admittingsteam to and exhausting it from the ends of the cylinder, and a passagefor conveying steam from the cylinder to the front end of thevalve-chest, said passage communicating with the cylinder through a mainport, and through a contracted passage which is opened to the steam inadvance of the opening of the main port, for the purposespecified.

2. An impact-tool in which are combined a cylinder, a valve-chest, areciprocating piston, a reciprocating valve, passages for admittingsteam to and exhausting it from the rear end of the cylinder, aninduction and exhaust passage leading from the valve-chest and havingtwo ports in the cylinder, one at the front end of the same, and onesome distance rearwardly from said front end, and a choke-plate locatedin said passage between said ports, the ports being so disposed thatthe, unobstructed port will be covered by the 1 piston while steam isbeing admitted through the valve, whereby the admission of steam to thefront end of the cylinder is wholly through the port controlled by thechoke-plate, but the exhaust of steam from said front end of thecylinder is through both ports, substantially as specified.

3. The combination in an impact-tool, of a cylinder having induction andeduction ports, a reciprocating piston in said cylinder, a valve chest,and a single valve contained therein, said valve controlling the exhaustfrom both ends of the cylinder and the inlet to the forward end of thesame, the inlet of steam to the valve-chest and to the rear end of thecylinder being controlled by the piston, substantially as specified.

4. The combination in an impact-tool, of a cylinder having areciprocating piston therein, a valve-ohest containing a valve adaptedto reciprocate therein, and ports and passages for admitting steamfromthe cylinder first to one end of the valve-chest and then to theother end of the same, the valve-chest having outlets at the ends onlythrough the passages by which steam enters the chest, the piston closingthe cylinder end of each inlet-port to the chest when the valve iscushioning, whereby steam trapped in either end of the chest is forcedto escape around the disk of the valve or the head of the piston,

orboth, substantially as specified.

5. The combination in an impact tool, of a cylinder having a pistonadapted to reciprocate therein, a valve-chest having an inductionportcommunicating with the forward end of the cylinder, and an exhaust-portcommunicating with the rear end of the cylinder,

and a valve adapted to reciprocate in said chest but so disposed inrespect to said ports.

that the exhaust-port will be opened in ad- Vance of the inlet-port,substantially as speci- In testimony whereof I have signed my name tothis specification in the presence of two subscribing witnesses.

I THOMAS H. PHILLIPS.

Witnesses:

WILL. A. BARR, J os. I-I. KLEIN.

